Reducing Light Pollution: Preserving Nature's Nighttime Beauty

Light pollution is the human-made alteration of outdoor light levels from those occurring naturally. It has harmful effects on wildlife, ecosystems, energy, climate change, human health, and safety. Light pollution can be reduced by adopting strong planning policies and taking individual action. For example, by using low-energy LED lamps, ensuring outdoor lights are fully shielded and directed downwards, and turning off lights when not in use. Reducing light pollution is important as it helps to protect wildlife, conserve energy, and restore the beauty of the night sky.

Protecting wildlife and ecosystems

Light pollution is the human-made alteration of outdoor light levels from those occurring naturally. It has harmful effects on wildlife and ecosystems.

Plants and animals depend on Earth's daily cycle of light and dark to govern life-sustaining behaviours such as reproduction, nourishment, sleep, and protection from predators. Scientific evidence suggests that artificial light at night has negative and deadly effects on many creatures, including amphibians, birds, mammals, insects, and plants.

Effects on nocturnal animals

Light pollution radically alters the nighttime environment for nocturnal animals, turning night into day. Predators use light to hunt, and prey use darkness as cover. Nocturnal animals that sleep during the day and are active at night are impacted by light pollution. For example, slow-flying bats avoid feeding in or passing through illuminated areas as it exposes them to predators such as owls and other birds of prey. Similarly, pumas travelling at night avoid brightly lit areas, causing them to miss crucial landscape linkages.

Effects on bird populations

Light pollution disorients nocturnal birds that use the moon and stars for navigation during their bi-annual migrations. They often crash into brightly lit buildings or towers, or circle them until they drop from exhaustion. Over 450 bird species that migrate at night across North America are susceptible to collisions with lit towers, including threatened or endangered species.

Effects on sea turtles

Beaches in sections of Florida's highly developed coastline are nesting grounds for rare loggerhead, leatherback, and green turtles. Bright lights nearby discourage females from coming ashore to nest, and newly hatched turtles need a dark night sky to orient themselves towards the sea. Artificial lights behind beaches lure them away, and millions of hatchlings die this way every year.

Effects on amphibians

The glare from artificial lights can impact wetland habitats that are home to amphibians such as frogs and toads, whose nocturnal croaking is part of their breeding ritual. Artificial lights disrupt this nocturnal activity, interfering with reproduction and reducing populations.

Effects on insects

Scientists say light pollution is among the factors driving a potentially catastrophic decline in some insect populations. Insects are drawn to light, and artificial lights create a fatal attraction. Declining insect populations negatively impact all species that rely on insects for food or pollination.

Effects on ecosystems

In addition to their ecological roles, some creatures impacted by light pollution, such as fireflies, are also a source of wonder and delight for humans. Light pollution can disrupt the natural balance of ecosystems, affecting food webs in unanticipated ways.

Reducing light pollution

Simple solutions can help reduce light pollution and protect wildlife and ecosystems. These include turning off unnecessary lights, using fewer lights inside, keeping blinds and drapes closed at night, and avoiding driving at night. When using lights outside, it is recommended to point them towards the ground to minimise light pollution and glare.

LED lights can also help reduce energy use and protect the environment, but only warm-coloured bulbs should be used to minimise the adverse effects of blue light on wildlife behaviour and reproduction.

Reducing energy use

Reducing light pollution is important for many reasons, including the negative impact it has on wildlife and ecosystems, energy use, and climate change.

Reducing light pollution can help to conserve energy and reduce energy costs. Here are some ways to reduce energy use and light pollution:

• Use only downward-facing lights: When light points upward, it contributes to artificial sky glow and light pollution. Install light shields for any outdoor lighting setups to help direct the light downward to a specific area.
• Use dimmers, motion sensors, and timers: These can help to reduce average illumination levels and save energy.
• Turn off unnecessary lights: Turn off indoor lights when not in use, especially in empty buildings at night. This will help prevent the leakage of interior light into the night sky.
• Use energy-efficient light bulbs: LED and compact fluorescent (CFL) light bulbs can help reduce energy use and protect the environment. Use warm-coloured bulbs to minimise blue and violet spectral components, which can aid night vision for all animals, including humans.
• Use only the lights you need: Avoid using more lights than you absolutely need. Having dim lighting or dimmers installed can help reduce overall light use.
• Keep blinds and drapes closed at night: Get into the habit of using window shades to keep room lights from escaping your house and contributing to light pollution outdoors.

Improving human health

Reducing light pollution is important for improving human health. Research suggests that artificial light at night can negatively affect human health, increasing the risks of obesity, depression, sleep disorders, diabetes, breast cancer, and more.

Humans evolved to the rhythms of the natural light/dark cycle of day and night. The proliferation of artificial light at night means most of us no longer experience truly dark nights. Many studies have shown that exposure to artificial light at night negatively affects human health. According to the American Medical Association, "It is estimated that white LED lamps have five times greater impact on circadian sleep rhythms than conventional street lamps."

Nighttime exposure to artificial light suppresses melatonin production, which is needed to keep us healthy. Melatonin has antioxidant properties, induces sleep, boosts the immune system, lowers cholesterol, and helps the functioning of the thyroid, pancreas, ovaries, testes, and adrenal glands.

Light pollution can also cause glare, which decreases vision by reducing contrast. This limits our ability to see potential dangers at night, and aging eyes are especially affected.

Additionally, light pollution can lead to over-illumination, which refers to the use of artificial light well beyond what is required for a specific activity, such as keeping the lights on all night in an empty office building. This not only wastes energy but also contributes to the negative health impacts of light pollution.

By reducing light pollution, we can minimize these negative effects on human health and create a healthier environment for ourselves and future generations.

Saving money

Reducing light pollution is important for many reasons, including saving money.

Reducing light pollution can lead to significant cost savings for individuals, businesses, and governments. Here are some ways in which reducing light pollution can save money:

• Reducing Energy Costs: Turning off unnecessary lights and using energy-efficient lighting technologies such as LEDs and compact fluorescents (CFLs) can substantially reduce energy consumption and lower electricity bills.
• Improving Energy Efficiency: By using shielded or covered bulbs that direct light downward, the same level of illumination can be achieved with less energy, resulting in cost savings.
• Minimizing Wasteful Lighting: Eliminating excessive decorative lighting during festive seasons, turning off indoor lights in empty buildings, and utilizing automated timers and systems to turn off street lights when natural lighting is sufficient can all help reduce unnecessary lighting and associated costs.
• Avoiding Costly Mistakes: Light pollution can have negative consequences for wildlife, including disrupting migration patterns and altering natural cycles. By reducing light pollution, we can avoid the financial costs associated with mitigating these impacts on ecosystems and wildlife habitats.
• Enhancing Public Safety: Excessive lighting can lead to glare and compromised vision for motorists and pedestrians, increasing the risk of accidents. By reducing light pollution and utilizing appropriate lighting technologies, public safety can be improved, potentially reducing costs associated with accidents and injuries.
• Promoting Energy Conservation: Initiatives to reduce light pollution often go hand in hand with energy conservation efforts. By encouraging the use of energy-efficient lighting, minimizing light trespass, and raising awareness about the impacts of light pollution, communities can reduce their overall energy consumption and associated costs.
• Supporting Responsible Lighting Practices: Organizations such as DarkSky International work to educate the public and promote responsible outdoor lighting practices. By following their guidelines and choosing DarkSky Approved lighting products, individuals and businesses can make cost-effective lighting choices that reduce light pollution.

Preserving spiritual and cultural practices

Light pollution is the presence of any unwanted, inappropriate, or excessive artificial lighting. It is a side effect of industrial civilization, and its sources include building exterior and interior lighting, advertising, outdoor area lighting, offices, factories, streetlights, and illuminated sporting venues.

Light pollution is actively destroying our ability to see the stars. Many Indigenous traditions and knowledge systems around the world are based on the stars, and the peoples' ability to observe and interpret stellar positions and properties is of critical importance for daily life and cultural continuity. The erasure of the night sky acts to erase Indigenous connection to the stars, acting as a form of ongoing cultural and ecological genocide.

In Australia, the cosmos serves as a foundation for numerous Indigenous knowledge systems and Origin stories. For Aboriginal and Torres Strait Islander people, the stars encode and communicate history, law, ethics, and moral values. Ngarinyin elder David Mowaljarlai said that “Everything is written twice – on the ground and in the sky”.

The celestial emu is one of the most widespread Aboriginal asterisms across Australia. It is not made up of the bright stars, but rather of the dark dust lanes in the Milky Way, between the Coalsack nebulae in Crux and the galactic centre in Scorpius and Sagittarius. The visibility and position of the emu in the sky throughout the year inform Aboriginal people about the behaviour of the bird (referencing both sexes, depending on the time of year it is visible), the changing seasons, navigational pathways, and social practices. This “dark constellation” - as well as the Magellanic Clouds, globular and open star clusters, nebulae, fainter stars, and aurorae - are being eradicated from view by increasing light pollution.

Traditionally, the concept of natural light pollution holds special significance to Aboriginal Australians. For example, the Gunnai people in east Gippsland, Victoria share oral traditions that describe the dynamic between the Moon man hunting the celestial emu. When the Moon rises in the sky, the glow of its light makes the emu “hide away”, but it returns to visibility when the Moon sets. However, human-made light pollution is impacting the visibility of the emu and other fainter celestial objects altogether, making them impossible to see in urban areas, regional cities, and remote communities.

The development of Dark Sky preserves around the world is helping to moderate this issue. The Warrumbungle National Park, home to Australia’s largest optical observatory at Siding Spring as well as Kamilaroi Aboriginal cultural sites linked to the Seven Sisters (Pleiades), is Australia’s first registered Dark Sky Park. Despite this status, the area is under significant threat from the glow of distant cities and the large flares from coal-seam gas in the Pilliga National Forest to the north.

Dark sky parks set criteria to ensure dark skies, such as the modification of lighting so that it faces downwards, fitting lights with shields, replacing or disconnecting upward-facing lights, placing lights in public areas on a timer to reduce the length of their use, and eliminating street lighting altogether in Dark Sky Park areas.

While these measures are highly beneficial, an increasing number of metropolitan and regional councils, commercial organisations, and private citizens are switching to LED lights due to their low energy usage, low cost, and apparent “green” status. Because of their low cost, more of these lights are being used, causing a greater increase in light pollution.

Many of the most commonly used LED lights emit a substantial portion of their light in the blue end of the spectrum, which is damaging to the visibility of the sky and to the health of humans and wildlife. Organisations such as the Australian Dark Sky Alliance and industrial lighting companies like WE-EF are working together to find solutions to this problem, which include the use of low-impact amber LEDs (which emit a majority of their light in the red/yellow end of the spectrum), covering street lights at the top to avoid direct exposure to the sky, angling street lights downward, and reducing overall light scatter.

The development of dark sky reserves is a great step towards raising awareness of the importance of preserving dark skies, particularly in rural areas. But light pollution is driven by economic growth and urban expansion, so substantial work is needed to improve and promote low-impact lighting in large population centers. An example of a community that has put a high priority on maintaining dark night skies is the city of Flagstaff, Arizona, which was designated a Dark Sky City in 2001. A major driving force behind this was the presence of numerous astronomical observatories in the area. The city’s policies enable the general public to see dark, clear skies from an urban center - something not afforded to people in most other metropolitan areas. If substantial and sustainable progress is to be made in preserving dark skies, more cities will need to address the way they light their communities, as light pollution affects skies far outside the metropolitan area.

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